CHICAGO (Reuters) - In another sign pointing to an
inherited component to autism, a study released on Monday found
that having a schizophrenic parent or a mother with psychiatric
problems roughly doubled a child's risk of being autistic.

"Our research shows that mothers and fathers diagnosed with
schizophrenia were about twice as likely to have a child
diagnosed with autism," said Julie Daniels of the University of
North Carolina, Chapel Hill, who worked on the study.

"We also saw higher rates of depression and personality
disorders among mothers, but not fathers," she said in a
statement.

The study of families in Sweden with children born between
1977 and 2003 involved 1,227 children diagnosed with autism.
They were compared with families of nearly 31,000 children who
did not have autism. Sweden's detailed health registry provides
a wealth of data for such studies.

ADVERTISEMENT

Autism, which is marked by impaired social interaction and
communication, or a related disorder like Asperger's syndrome,
affects an estimated one out of every 150 U.S. children, the
U.S. Centers for Disease Control and Prevention estimates.
Asperger's is marked by mild social awkwardness.

No one knows what causes autism, but researchers think it
is likely that several genes and possibly environmental factors
contribute. Some autism advocates believe childhood
vaccinations play a role, although most medical experts say it
is extremely unlikely.

Which genes lie behind various mental illnesses are also
poorly understood, according to the researchers, whose study
appeared in the journal Pediatrics, published by the American
Academy of Pediatrics.

"Earlier studies have shown a higher rate of psychiatric
disorders in families of autistic children than in the general
population," Daniels said.

The association between a child's autism and mental illness
in the parent was strongest with schizophrenia, and was less
powerful when the mother suffered from depression or
personality disorders. There was little association between
autism and parental addiction to alcohol or drugs or some other
types of mental illness.

It was not clear if it was significant that having a
mother, but not a father, with certain mental illnesses, raised
the risk of autism.

"Establishing an association between autism and other
psychiatric disorders might enable future investigators to
better focus on genetic and environmental factors that might be
shared among these disorders," Daniels said.